1. Field of the Invention
The present invention relates to a device for dosing a gas, particularly in a ventilator system.
2. Description of the Prior Art
Supply of an additive gas by means of a dosing tube is described, for example, in PCT Application WO 91/19526. The intention is, in this case, to reduce the re-breathing of carbon dioxide. Fresh dry gas can be transported down to the trachea in order to flush away exhaled gas which comes from the lungs and which would normally be re-breathed with the next breath (dead space).
The supply of dry gas can result in dehydration of a patient. This is especially the case if large quantities of dry gas are supplied in this manner. This is not desirable and can result in injury to the patient.
Another purpose for the delivery of an additive gas can be to provide therapy in the form of high frequency pulses superimposed on normal ventilation, such as is described in PCT Application WO 82/03014. In this case the additive high frequency gas may be humidified before it is introduced into the tubing system of the medical ventilator. This is done mainly because larger gas amounts are involved than normally occur in the applications according to WO 91/19526.
Active humidification of an additive gas, however, means additional costs because the humidifier must be monitored, etc. Risk to the patient increases in the event of the active humidifier ceasing to function.
There is thus a need for a simple, inexpensive and effective solution to these problems.